It changes the angle of the face due to the sensor of the camera being able to see a higher Field of View (FOV). The higher the FOV (lower the zoom) the more the lens distorts the perceived image, this usually causes central objects to appear closer to the picture plane while the closer to the edge of the picture (lens) the 'longer' things appear to be. So without lens correction being applied to a image like the 24mm zoom you get lens distortion. This lens distortion changes how the face appears as things closer to the lens or near the edge will become distorted. The more you know.